Make a new InputComponent that can be re-used everywhere to make all text accept the same kind of input

src/Faction/ui/DonateOption.tsx

@@ -20,7 +20,7 @@ import { MathJaxWrapper } from "../../MathJaxWrapper";
 import Typography from "@mui/material/Typography";
 import Paper from "@mui/material/Paper";
 import Button from "@mui/material/Button";
-import TextField from "@mui/material/TextField";
+import { NumberInput } from "../../ui/React/NumberInput";
 
 type IProps = {
   faction: Faction;
@@ -31,26 +31,20 @@ type IProps = {
 };
 
 export function DonateOption(props: IProps): React.ReactElement {
-  const [donateAmt, setDonateAmt] = useState<number | null>(null);
+  const [donateAmt, setDonateAmt] = useState<number>(NaN);
   const digits = (CONSTANTS.DonateMoneyToRepDivisor + "").length - 1;
 
   function canDonate(): boolean {
-    if (donateAmt === null) return false;
+    if (isNaN(donateAmt)) return false;
     if (isNaN(donateAmt) || donateAmt <= 0) return false;
     if (props.p.money < donateAmt) return false;
     return true;
   }
 
-  function onChange(event: React.ChangeEvent<HTMLInputElement>): void {
-    const amt = numeralWrapper.parseMoney(event.target.value);
-    if (event.target.value === "" || isNaN(amt)) setDonateAmt(null);
-    else setDonateAmt(amt);
-  }
-
   function donate(): void {
     const fac = props.faction;
     const amt = donateAmt;
-    if (amt === null) return;
+    if (isNaN(amt)) return;
     if (!canDonate()) return;
     props.p.loseMoney(amt, "other");
     const repGain = repFromDonation(amt, props.p);
@@ -85,8 +79,8 @@ export function DonateOption(props: IProps): React.ReactElement {
         </Typography>
       ) : (
         <>
-          <TextField
+          <NumberInput
-            onChange={onChange}
+            onChange={setDonateAmt}
             placeholder={"Donation amount"}
             disabled={props.disabled}
             InputProps={{

src/ui/React/NumberInput.tsx

@@ -0,0 +1,19 @@
+import { TextField, StandardTextFieldProps } from "@mui/material";
+import React from "react";
+import { numeralWrapper } from "../numeralFormat";
+
+interface IProps extends Omit<StandardTextFieldProps, "onChange"> {
+  onChange: (v: number) => void;
+}
+
+export function NumberInput(props: IProps): React.ReactElement {
+  const textProps = {
+    ...props,
+    onChange: (event: React.ChangeEvent<HTMLInputElement>) => {
+      const amt = numeralWrapper.parseMoney(event.target.value);
+      if (event.target.value === "" || isNaN(amt)) props.onChange(NaN);
+      else props.onChange(amt);
+    },
+  };
+  return <TextField {...textProps} />;
+}